System and method for thermally robust energy storage system

ABSTRACT

Various systems for cooling a battery cell array are described. In one example an energy storage system includes a housing enclosing a battery cell array, an evaporator, and a circulating pump. In another example, an evaporator is adjacent to battery cells to facilitate heat transfer. In another example, thermoelectric elements are positioned adjacent to battery cells to facilitate heat transfer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/845,758filed Sep. 4, 2015, which is a continuation of International PatentApplication No. PCT/US2014/020986 filed Mar. 6, 2014, which claims thebenefit of U.S. Provisional Application No. 61/782,282 filed Mar. 14,2013, which is hereby incorporated by reference in its entirety.

BACKGROUND

The present invention generally relates to an energy storage system, andmore particularly, to an energy storage module to be incorporated into ahybrid electric motor vehicle to store high voltage energy.

Vehicles incorporating electric motors require high voltage energystorage systems in order to properly power the motor. High voltageenergy storage often encompasses multiple battery cells which areelectrically connected together in series. Storage cells, when chargingor discharging generate heat due to chemical reactions within the cells,as heat generation is a byproduct of electricity generation. Whenmultiple battery cells are contained in close proximity, as in an array,the heat generated in each cell can become multiplicative throughout thesystem and can cause problems such as cell thermal runaway which candestroy the storage system. Additionally, for optimal energy efficiency,uniform temperature of the battery cells is preferred. Thus it isadvantageous for such storage systems to include a cooling system tocool the battery cells.

Commonly, hybrid and electric energy storage cooling systems use an opensystem design which allows external air to reach the battery cells.Often these systems use convective heat transfer to reduce thetemperatures of the batteries by passing air over the batteries whichcirculates from an external intake to an external exhaust. These systemsare susceptible to problems caused by salt, dust, and other debris thatcan reach the battery cells by entering the air intake. Open coolingsystems do not prevent salt fog or other corrosive materials fromreaching the battery cells, even when a filter is used. Salt fog andforeign particles can cause corrosion and unwanted electrical leakagecurrent paths or short circuits to exist in the storage system.Correspondingly, the system can cause a reduced battery cell lifecompared to a closed system. Open cooling systems can necessitateinstallation and use of drain plugs to remove foreign substances fromthe battery enclosure. Additionally, open cooling system designs addvolume to the battery array system which causes problems withspace-efficient original designs or hybrid retrofit applications.

The above problems as well as other problems with open cooling systemsdemonstrate a need in the field for alternative cooling systems forbattery cell arrays such as various types of closed cooling systems.

SUMMARY

The energy storage systems described herein address several of theissues mentioned above as well as others. The energy storage systemsinclude a housing containing an array of battery cells. The energystorage systems are closed systems such that the internal environmentsare hermetically sealed. The energy storage systems are designed toprovide rapid and efficient heat transfer from the battery cells to theexterior of the housings.

In one example, an evaporator and air circulator are positioned withinthe housing. The evaporator can include of a series of evaporator coilsintegrated with a plurality of cooling fins. The air circulator caninclude a scroll-type fan. The air circulator and evaporator workcooperatively to enable rapid and efficient thermal energy transfer byproviding a thermal energy flow path from the battery cells to arefrigerant located in the evaporator.

In other examples, a thermal transfer plate is positioned at the base ofthe battery cells. An evaporator or evaporator coils are positionedadjacent to the thermal transfer plate. The evaporator workscooperatively with the thermal transfer plate to enable rapid andefficient thermal energy transfer by providing a thermal energy flowpath from the battery cells to a refrigerant located in the evaporator.

In another example, a thermal transfer plate is positioned at the baseof the battery cells. A series of thermoelectric elements are positionedadjacent to the thermal transfer plate. The thermoelectric elements workcooperatively with the thermal transfer plate to enable rapid andefficient thermal energy transfer by providing a thermal energy flowpath from the battery cells to a refrigerant located in the evaporator.

Further forms, objects, features, aspects, benefits, advantages, andexamples of the present disclosure will become apparent from a detaileddescription and drawings provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of an energy storage system.

FIG. 2 illustrates a top view of an energy storage system with the lidremoved.

FIG. 3 illustrates a partial perspective view of an energy storagesystem with the lid removed.

FIG. 4 illustrates a partial cross-sectional side view of an energystorage system.

FIG. 5 illustrates a partial perspective view of an energy storagesystem without walls or a lid.

FIG. 6 illustrates a partial perspective view of an energy storagesystem without walls or a lid.

FIG. 7 illustrates a partial perspective view of an energy storagesystem without walls or a lid.

DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings, and specific language will be used to describe the same.It will nevertheless be understood that no limitation of the scope ofthe invention is thereby intended. Any alterations and furthermodifications in the described embodiments and any further applicationsof the principles of the invention as described herein are contemplatedas would normally occur to one skilled in the art to which the inventionrelates. It will be apparent to those skilled in the relevant art thatsome features not relevant to the present invention may not be shown forthe sake of clarity.

With respect to the specification and claims, it should be noted thatthe singular forms “a”, “an”, “the”, and the like include pluralreferents unless expressly discussed otherwise. As an illustration,references to “a device” or “the device” include one or more of suchdevices and equivalents thereof. It also should be noted thatdirectional terms, such as “up”, “down”, “top”, “bottom”, and the like,are used herein solely for the convenience of the reader in order to aidin the reader's understanding of the illustrated embodiments, and it isnot the intent that the use of these directional terms in any mannerlimit the described, illustrated, and/or claimed features to a specificdirection and/or orientation.

The reference numerals in the following description have been organizedto aid the reader in quickly identifying the drawings where variouscomponents are first shown. In particular, the drawing in which anelement first appears is typically indicated by the left-most digit(s)in the corresponding reference number. For example, an elementidentified by a “100” series reference numeral will first appear in FIG.1, an element identified by a “200” series reference numeral will firstappear in FIG. 2, and so on.

FIG. 1 shows a perspective view of an energy storage system 100. Theenergy storage system 100 is adapted for use in hybrid vehicles as wellas other types of vehicles or transportation systems and it is alsoenvisioned that various aspects of the energy storage system 100 can beincorporated into other environments. In the context of a hybridvehicle, the energy storage system 100 receives electrical energy whichis generated by an electric motor/generator (not shown). The energystorage system 100 also conversely supplies energy to the electricmotor/generator and also to other components such as an inverter, aDC-DC converter, or other components. The energy storage system 100communicates with an electric motor/generator and other componentsthrough the use of high voltage wiring.

The energy storage system 100 includes a housing 102 which providesstructural support for the energy storage system 100. The housing 102includes a plurality of walls 104, a floor (not shown) and a lid 106.The housing 102 generally forms a rectangular shape including four walls104. The walls 104, floor, and lid 106 provide structural support forthe housing 102. The seals between the walls 104, the lid 106, thefloor, and other structural aspects of the housing 102 create ahermetically and fluidly sealed environment within the housing 102. Theseals can be any seals which are generally known in the art and capableof withstanding high temperature variances and ranges and such as weldsor polymer seals.

Located at one end of the housing 102 is a high voltage junction box 108which facilitates electric signal connections from the energy storagesystem 100 to an electric motor/generator, inverter, DC-DC converter, orother components which may be part of an electric hybrid vehicle.Although the housing 102 depicted in FIG. 1 is shown as a generallyrectangular shape, the depiction is for illustration purposes only, andthe housing 102 could be formed as any of a variety of shapes. Thehousing 102 is preferably constructed of materials having advantageousthermal properties such as aluminum, steel, magnesium, or other types ofmetals or non-metals. Additionally, the walls 104 can be constructed ofa material that has a high resistance to heat and that is structurallysound when undergoing temperature variations or exposure to variedtemperature ranges.

Included in at least one wall 104 is a pressure relief valve (notshown). In the case of an increase of internal pressure beyond a targetthreshold, the pressure relief valve allows gas or fluid to be releasedfrom within the housing and prevents cracking or other failure of thehousing 102. The pressure relief valve works in one direction and doesnot allow external air or water inside the enclosure.

FIG. 2 shows a cutaway top view drawing of the energy storage system 100with the lid 106 removed. Located within the interior of the housing 102are battery cell arrays 200, a scroll fan 202, and an evaporator 204.The scroll fan 202 is positioned centrally relative to the battery cellarrays 200. Similarly the evaporator 204 is positioned centrallyrelative to the battery cell arrays 200. The evaporator 204 and scrollfan 202 can be positioned in a variety of configurations within thehousing 102.

The battery cell arrays 200 are in essence linked groups ofelectrochemical batteries for storing energy generated by an electricmotor/generator and rapidly supplying the energy back to an electricmotor/generator. While the illustrated example shows the energy storagesystem 100 including two battery cell arrays 200, the energy storagesystem 100 can include more or fewer battery cell arrays 200 than areshown. The battery cell arrays 200 include individual battery cellswhich may be daisy chained together in series or parallel according theparticular system. The battery cell arrays 200 are connected by signallinks which provide an electrical connection and facilitatecommunication between the various battery cell arrays 200. Similarly,signal links connect the battery cell arrays 200 to the high voltagejunction box 108. The data links can include any electrical connectorsand signal carriers which are known in the art and suitable fortransporting electrical signals in a variable-temperature environment.The individual battery cells of the battery cell arrays 200 includebattery walls that seal the internal components of the battery cells.The battery walls are generally constructed from a material such asaluminum, or other metal or non-metal material having high thermalconductivity such that heat energy generated within the battery cellscan be rapidly transferred to the exterior surfaces of the batterywalls.

FIG. 3 shows a partial perspective view of the energy storage system 100with the lid 106 removed. The energy storage system 100 further includestubes 300 which are fluidly connected to the evaporator 204. The tubes300 provide a pathway for fluid to travel through the walls 104. Thetubes 300 are sealingly integrated with the walls 104 in order tomaintain the hermetic integrity of the interior of the housing 102 suchthat no air can pass through the walls 104 at the point where the tubes300 pass through the walls 104. The seals can be any of a variety ofseals which are known in the art and suitable for variable temperatureenvironments such as compression seals, o-rings, or polymer seals forexample.

The scroll fan 202 causes the air within the housing 102 to circulatethroughout the housing 102. The scroll fan 202 is shown as being locatedabove the evaporator 204 in a central position relative to the batterycell arrays 200. The depiction of the scroll fan 202 is for illustrationpurposes only and the scroll fan 202 could be located at other parts ofthe housing 102. The scroll fan 202 circulates the air throughout theinterior of the housing 102 such that the air flows at a generallyuniform circulation rate along a flow path through the interior of thehousing 102.

The scroll fan 202 is configured as a centrifugal-type pump.Alternatively, the scroll fan 202 can be a positive displacement pumpwhich converts external power to motion of a pump mechanism and causesair to flow through an inlet and outlet. Alternatively, the scroll fan202 could also be a basic propeller that converts rotational motion intoforced fluid flow or any other variety of mechanism which are suitablefor causing fluid circulation within the housing 102. The scroll fan 202can also be any of a variety of air circulators which cause fluidmovement and which are known in the art.

The scroll fan 202 is supported by a support member 302 which ispositioned within the housing 102. The support member 302 provides asupport surface for the scroll fan 202 as well as providing a fluidpassageway whereby the scroll fan 202 can cause air to circulate amongthe battery cells. The support member 302 can provide support for theevaporator 204 or alternately the support member 302 can be attached toand supported by the evaporator 204.

FIG. 4 shows a partial side cross-sectional view of the energy storagesystem 100. The evaporator 204 can be any of a variety of evaporatorswhich are suitable for use in refrigeration systems such as, forexample, a series of wound evaporator coils 400. The evaporator coils400 are positioned between the two battery cell arrays 200. Theevaporator 204 can include cooling fins 402 which are integrated withthe evaporator coils 400. The cooling fins 402 are configured as aseries of planar objects which are positioned in a parallelconfiguration relative to each other. The evaporator coils 400 extendthrough holes or cutouts in the cooling fins 402 such that theevaporator coils 400 abut against the cooling fins 402. In this way,thermal heat transfer is enabled between the evaporator coils 400 andcooling fins 402. The cooling fins 402 are constructed of a materialsuch as aluminum, or other metal or non-metal material having highthermal conductivity.

The energy storage system 100 is configured to create a thermal energytransfer path whereby the energy storage system 100 efficientlytransfers heat energy from the battery cells to the exterior of thehousing 102. Generally, the evaporator 204 is part of a refrigerationsystem whereby the evaporator 204 absorbs thermal heat energy from thebattery cells. The scroll fan 202 is configured to circulate air withinthe housing 102 and more particularly across the cooling fins 402 of theevaporator 204. In this way the scrolling fan 202 increases a convectiveheat transfer rate occurring at the interface of the cooling fins 402and the air within the housing 102.

More specifically, the evaporator 204 is part of a refrigeration systemwhich includes a compressor, condenser, expansion valve and theevaporator 204. The components of the refrigeration system are connectedtogether by a fluid-carrying line which generally carries a refrigerant.The refrigeration system operates as a vapor compression cycle in whichthe refrigerant travels through the refrigerant line and passes throughthe four components (the compressor, the condenser, the expansion valve,and the evaporator 204). The refrigerant undergoes a thermodynamictransformation during each phase of the vapor compression cycle. Therefrigerant can be any of a variety of substances which are suitable foruse in a refrigeration cycle such as ammonia or methane.

As part of the refrigeration cycle, the refrigerant enters theevaporator 204 through a tube 300 from an expansion valve as a liquidvapor mixture at a low pressure and low temperature. The refrigerant hasa boiling point which is below a target temperature of the interior ofthe housing 102 such that the refrigerant will necessarily evaporate (orboil) during the evaporation phase. The evaporator 204 enablessufficient thermal contact between the cooling fins 402 and the airinside the housing 102 for the refrigerant to absorb heat energy fromthe cooling fins 402 and the air. The walls of the evaporator coils 400are preferably made of a material having high thermal conductivity suchas aluminum, for example, in order to maximize the heat energy transferrate between the refrigerant and the cooling fins 402. Within theevaporator 204, the refrigerant undergoes thermal heat energy transferwith the cooling fins 402 and the air. Because the refrigeranttemperature is lower than the mean temperature of the air as well as thecooling fins 402, thermal heat energy flows from the air and coolingfins 402 to the refrigerant. Because the refrigerant is at a lowpressure, the refrigerant is able to boil at a low temperature and therefrigerant becomes vaporized. Once vaporized, the refrigerant continuesthrough the tubes 300 and exits the housing 102 where it enters acompressor.

The scroll fan 202 works in conjunction with the evaporator 204 toremove heat energy from the battery cells and also from the energystorage system 100 generally. By causing the air within the housing 102to circulate within the housing, the air cannot become stagnant suchthat the portion of air directly surrounding the evaporator coils 400would become generally lower in temperature than the mean temperature ofthe air within the housing 102. The scroll fan 202 ensures that the airwhich flows across the cooling fins 402 and the evaporator coils 400 isof sufficiently high temperature to maximize the heat energy transferrate from the air to the refrigerant travelling through the evaporatorcoils 400.

As will be appreciated by those skilled in the art, the rate of heattransfer by convection from one medium to another is directlyproportional to the surface area of the medium from which heat energy istransferred as well as the difference in temperature between the twomediums. Additionally, the rate of heat transfer by conduction betweentwo points is directly proportional to the difference in temperaturebetween the two points and the thermal conductivity of the mediumthrough which the heat energy is being transferred. The energy storagesystem 100 is designed to increase heat energy transfer from the batterycells to the refrigerant. The cooling fins 402 present an increasedamount of surface area through which the convective heat transfer ratefrom the air within the housing 102 to the refrigerant in the evaporator204 is increased. Through use of the cooling fins 402, an increasedamount of heat energy is transferred conductively to the evaporatorcoils 400 and subsequently to the refrigerant in the evaporator 204. Inthis way, the cooling fins 402 work in conjunction with the scroll fan202 to cause an increased heat energy transfer rate from the batterycells to the refrigerant within the evaporator 204.

Through testing, it was determined that with an appropriately sized 12vdc or 24 vdc refrigeration system, a total steady-state heatdissipation of 600 W can be achieved while maintaining battery celltemperatures below 45 degrees Celsius. According to this analysis, thescroll fan 202 imparts 30 cfm to 40 cfm of air circulation through theevaporator and across the battery cells.

It is understood by those skilled in the art that high-voltage batterycells daisy-chained together in close proximity can generate asubstantial amount of heat energy when charging or discharging. The heatenergy buildup within the battery cell arrays 200 causes heat energy tobe conductively transferred to the individual battery walls. In thisway, at various times during operation of the energy storage system 100,if no heat energy management system is in place, the battery cells andbattery walls could reach substantially high temperatures and causecatastrophic failure to the system. For example, cell thermal runawaycould occur when rising temperatures of a battery cell causes a chemicalreaction in which further heat energy is released within the batterycell. Further, the heat energy from one battery cell undergoing cellthermal runaway could spread to adjacent battery cells, subsequentlycausing an increased temperature in the adjacent battery cells. In thisway, a chain reaction of multiple failing battery cells within theenergy storage system 100 could occur. A battery failure could cause gasto be released from the battery cell into the housing 102, increasingthe internal pressure of the sealed housing 102. If the internalpressure increases beyond a pre-determined threshold, the pressurerelief valve activates and prevents further failure of the energystorage system 100. Yet the pressure relief valve is a backup systemonly, as the energy storage system 100 includes a means for rapid andefficient heat energy transfer from the battery cell arrays 200 to theexterior of the housing 102, thereby preventing an overheating scenario.

An alternative example of the current concept is shown in FIG. 5. FIG. 5shows a partial perspective view of an energy storage system 500 havingtwo rows of battery cell arrays 200. The energy storage system 500 isgenerally constructed having walls and a lid as described previously butwhich are not shown in FIG. 5. The energy storage system 500 is a closedsystem such that the interior of the energy storage system 500 ishermetically sealed from the exterior environment. The energy storagesystem 500 includes a thermal transfer plate 502 at the base of theenergy storage system 500. Also included is an optional dielectric layer504. The thermal transfer plate provides support for the battery cellarrays 200 as well as other components located within the energy storagesystem 500. The thermal transfer plate 502 generally extends along theentirety of the bottom surface of the battery cell arrays 200. Thethermal transfer plate 502 is generally constructed of a metal or othermaterial having a high thermal conductivity such as aluminum forexample.

The dielectric layer 504 is generally positioned between the thermaltransfer plate and the battery cell arrays 200. The dielectric layer 504extends along the thermal transfer plate 502 at least to the extent thatit extends throughout the entirety of the base of the battery cellarrays 200. The dielectric layer provides a layer of electric insulativeprotection between the battery cell arrays 200 and the thermal transferplate 502. Any of a variety of dielectric materials can be used for thedielectric layer 504 such as a variety of plastics, glass, porcelain andother materials. Preferably, the dielectric layer 504 also has highthermal conductivity such that it provides thermal transfer between thebattery cell arrays 200 and the thermal transfer plate 502. Preferably,the dielectric layer 504 has a thickness of 1 mm. The dielectric layer504 can also have a thickness greater or less than 1 mm.

FIG. 6 shows an alternative perspective view of the energy storagesystem 500. The energy storage system 500 also includes an evaporatorhaving evaporator coils 600. The evaporator coils 600 are positionedalong a surface of the thermal transfer plate 502 such that they abutthe thermal transfer plate 502. The evaporator coils 600 include fluidtransfer tubes 602. The evaporator and evaporator coils 600 are part ofa refrigeration system including a compressor, condenser and expansionvalve operating under a vapor compression cycle as described previously.The arrangement of the evaporator coils 600 shown in FIG. 6 are forillustrative purposes only and any of a variety of coil arrangementscould be used. The evaporator coils 600 are configured to carry arefrigerant which enters and exit the coils through the tubes 602. Theevaporator coils 600 and thermal transfer plate 502 can be locatedwithin the interior of the energy storage system 500 such that theevaporator coils 600 are within the hermetically sealed portion of theenergy storage system 500. Alternatively, the evaporator coils could belocated external to the hermetically sealed interior of the energystorage system 500 such that the thermal transfer plate provides athermal energy pathway from the interior of the energy storage system tothe exterior of the energy storage system.

As described previously, the evaporator coils 600 carry a lowtemperature refrigerant which provides a conductive heat transferpathway from the battery cell arrays 200 to the refrigerant within theevaporator coils 600. As discussed previously, as the battery cellsgenerate heat, the heat energy must be dissipated to avoid catastrophicfailure. Due to the difference in temperature between the battery cellsand the refrigerant in the evaporator coils 600, a thermal pathway iscreated whereby the heat energy is transferred from the battery cellarrays 200 through the thermal transfer plate 502, through the walls ofthe evaporator coils 600 and to the refrigerant. In this way the energystorage system 500 provides an efficient means to transfer heat energyfrom the battery cell arrays 200.

An alternative example of the current concept is shown in FIG. 7. FIG. 7shows a perspective view of an energy storage system 700 having twobattery cell arrays 200. The energy storage system 700 is generallyconstructed having walls and a lid as described previously but which arenot shown in FIG. 7. The energy storage system 700 is a closed systemsuch that the interior of the energy storage system 700 is hermeticallysealed from the exterior environment. The energy storage system 700includes a thermal transfer plate 502 at the base of the energy storagesystem 700. Also included is an optional dielectric layer 504 aspreviously described. The thermal transfer plate 502 provides supportfor the battery cell arrays 200 as well as other components locatedwithin the energy storage system 700. The thermal transfer plate 502generally extends along the entirety of the bottom surface of thebattery cell arrays 200. The thermal transfer plate 502 is generallyconstructed of a metal or other material having a high thermalconductivity such as aluminum for example.

Located on the bottom of the thermal transfer plate 502 are a series ofthermoelectric elements 702. The thermoelectric elements 702 are of atype that uses a heat flux between the junctions of two different typesof materials. The thermoelectric elements 702 can be any of a variety ofcoolers, one of which is a Peltier type element in which p-type andn-type semiconductors are thermally arranged in parallel andelectrically arranged in series. When a current is caused to flowthrough the Peltier element, heat absorption and heat dissipation occuron the differing surfaces due to the Peltier effect. By applying anelectric potential to the thermoelectric elements 702, a temperaturedifferential is achieved where the bottom surface 704 of thethermoelectric elements 702 is maintained at a higher temperature thanthe top surface of the thermoelectric elements 702. By maintaining alower temperature on the top surface of the thermoelectric elements 702,a thermal pathway is created from the battery cell arrays 200 to thethermoelectric elements 702. In this way, the heat energy flows from thebattery cells, through the thermal transfer plate 502 and to thethermoelectric elements 702.

The thermoelectric elements 702 can be arranged as shown in FIG. 7 oralternatively they can be arranged in a variety of differentarrangements. Additionally, a variety of different quantities ofthermoelectric elements 702 can be used. For example, two thermoelectricelements 702 could be used or eight or sixteen thermoelectric elements702 could be used. The energy storage system 700 can be constructed suchthat the battery cell arrays and thermoelectric plate are located withina hermetically sealed environment while the thermoelectric elements 702are located outside or exterior relative to the hermetically sealedenvironment.

The concept described herein and various embodiments are configured tobe used with a controller and other electrical hardware that providescontrol functions for the energy storage systems. For example, thecontroller controls the operation of the scroll fan 202 as well asoperation of the evaporator coils 400. Typically, a variety of sensorswill be located within each energy storage system such as temperatureand pressure sensors and as well as voltage and other power sensors.Controllers additionally supply electric energy power and signals tovarious components such as the thermoelectric elements 702.

When used with a vehicle, the evaporator and refrigeration systemdescribed herein can include a complete vapor compression cycle andcomponents which are solely dedicated to the energy storage system andlocated in components external to the energy storage systems andhousings described herein. Alternatively, the evaporators can also becombined with a condenser which serves other purposes within a vehicle.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes, equivalents, and modifications that come within the spiritof the inventions defined by the following claims are desired to beprotected. All publications, patents, and patent applications cited inthis specification are herein incorporated by reference as if eachindividual publication, patent, or patent application were specificallyand individually indicated to be incorporated by reference and set forthin its entirety herein.

What is claimed is:
 1. An apparatus comprising: a housing; a firstbattery cell array positioned inside the housing; a second battery cellarray positioned inside the housing so that the first battery cell arrayand the second battery cell array extend substantially parallel to eachother; a thermal transfer plate, wherein the first battery cell arrayand the second battery cell array are positioned adjacent to a firstside of the thermal transfer plate; and a plurality of thermoelectricelements adjacent to a second side of the thermal transfer plate,wherein the thermal transfer plate is coupled to the housing; andwherein the plurality of thermoelectric elements are arranged so thatthere is a first row of thermoelectric elements aligned with the firstbattery cell array and a second row of thermoelectric elements alignedwith the second battery cell array.
 2. The apparatus of claim 1, whereinthe first battery cell array is positioned in contact with the thermaltransfer plate.
 3. The apparatus of claim 1, wherein the plurality ofthermoelectric elements are in direct contact with the second side ofthe thermal transfer plate.
 4. The apparatus of claim 1, wherein thefirst side of the thermal transfer plate is inside the housing, andwherein the second side of the thermal transfer plate is outside thehousing.
 5. The apparatus of claim 1, wherein the thermoelectric elementis a Peltier type element.
 6. The apparatus of claim 1, wherein thehousing further comprises: at least one wall; a cover; and a floor,wherein the floor includes the thermal transfer plate, wherein the firstand second battery cell arrays are adjacent to the floor, and whereinthe floor, the cover, and the at least one wall are arranged andconfigured to enclose the first battery cell array and the secondbattery cell array.
 7. The apparatus of claim 6, wherein the housingfurther comprises: a sealing member, wherein the sealing member ispositioned between the cover and the at least one wall, and wherein thehousing is hermetically sealed.
 8. The apparatus of claim 6, wherein thefloor includes the thermal transfer plate.
 9. The apparatus of claim 1,wherein the thermal transfer plate extends along the entirety of thebottom surface of the first battery cell array.
 10. The apparatus ofclaim 1, wherein the thermoelectric element uses a heat flux between thejunctions of two different types of materials to create the temperaturedifferential in the thermoelectric element.
 11. The apparatus of claim1, wherein the second side of the thermal transfer plate is the bottomof the thermal transfer plate and wherein the plurality ofthermoelectric elements are in contact with the bottom of the thermaltransfer plate.
 12. The apparatus of claim 1, wherein the thermaltransfer plate extends along the entirety of the bottom surface of thesecond battery cell array.
 13. The apparatus of claim 1, furthercomprising: a controller electrically connected to the thermoelectricelement, wherein the controller is configured to control an electriccurrent to the thermoelectric element; and wherein the electric currentsupplied to the thermoelectric element causes a temperature differentialin the thermoelectric element that creates a thermal pathway between thefirst and second battery cell arrays and the plurality of thermoelectricelements.
 14. The apparatus of claim 1, wherein the plurality ofthermoelectric elements are positioned exterior to the housing.